Engine system components (such as cylinders, valves, pistons, injectors, etc.) may be intermittently diagnosed for damage incurred during engine operation. The components may also be diagnosed to identify degraded functionality (e.g, incorrect flow, leakage, etc.). Diagnostics may involve visually inspecting the components for scoring damage, such as by removing a spark plug and obtaining a bore scope to view inside the cylinder. In another approach, described by Yalin et al in US 2006/0037572, light from a cylinder spark event and/or combustion flame is used to diagnose for the presence of build-up and contaminants in the cylinder.
The inventors herein have recognized that the above discussed approaches can add extensive time, cost, and complexity to the diagnostics. In particular, most of the above approaches require a skilled technician, complex diagnostic tools, specialized laboratory facilities, and time consuming engine teardown. As a further example, Yalin diagnoses the cylinder using the light generated during combustion, and therefore is unable to diagnose cylinder events occurring before combustion initiation. In view of these issues, the inventors have realized that in engine systems configured with laser ignition capabilities, components of the laser ignition system can be advantageously used to diagnose various engine system components. In one example, the engine may be diagnosed by a method comprising: operating a laser ignition device during an intake stroke of a cylinder at lower power; and indicating degradation of a cylinder component based on output from a photodetector coupled to the cylinder, the output generated during the intake stroke following operation of the laser ignition device. In this way, engine cylinder diagnostics can be expedited and simplified without necessitating engine disassembly.
For example, the optics of a laser ignition system can be used to diagnose the cylinder. The lasers may be used to rapidly sweep the interior of each cylinder. In particular, low power light pulses may be emitted by the laser ignition device into the cylinder during an intake stroke and detected by a photodetection system coupled to the head of the cylinder. The photodetection system may include a camera (such as a CCD camera) and a lens (such as a fish-eye lens), for detecting the light pulses. In one example, the light pulses may be emitted in the infra-red (IR) spectrum by the laser ignition device, and detected in the IR spectrum by the camera. Images of a condition of the interior of the cylinder during the intake stroke may then be generated based on the detected pulses. The images may be indicative of, for example, a fuel injector spray pattern, intake airflow pattern, presence of an obstruction (e.g., due to particulate matter or a foreign object) in the cylinder, etc., and may be used to infer the condition of cylinder components such as cylinder intake valve, fuel injector, piston rings, etc. The images may be transmitted (e.g., wirelessly) within the engine system and displayed to a service provider (e.g., mechanic or vehicle operator) on a display of a vehicle center-console. In addition, a reference image of the component being diagnosed may be retrieved from the controller's memory and displayed to the mechanic for comparative analysis. For example, when the image generated is indicative of a fuel injector spray pattern, the reference image displayed may be indicative of an expected fuel injector spray pattern. Optionally, if the engine is coupled in a hybrid electric vehicle, an electric motor may be operated during engine operation to maintain engine speed-load conditions while the in-cylinder images are generated. If the mechanic determines that the generated image is sufficiently different from the reference image, the mechanic may determine that there is component degradation and may indicate the same to the controller via the display device. Accordingly, a diagnostic code may be set.
In this way, it may be possible to take advantage of a laser ignition system to reduce the time and cost associated with the visual inspection of an engine, without reducing the accuracy of the inspection. By comparing cylinder images gathered by a photodetector during an intake stroke of a cylinder, various cylinder components can be diagnosed. The diagnostic images generated can be displayed to a mechanic, along with reference images for comparison, so that the mechanic can identify cylinder component degradation. By using hardware already available in an engine configured with a laser ignition system, the need for costly, labor intensive, and time-consuming visual inspections can be reduced. By taking in-cylinder images during an intake stroke (in addition to taking images using the light from cylinder combustion), a wider variety of cylinder component degradation conditions can be identified. Overall, engine inspection can be simplified without reducing inspection accuracy.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.